/******************************************************************************
 * FILE: mpi_ping.c
 * DESCRIPTION:
 *   MPI tutorial example code: Blocking Send/Receive
 * AUTHOR: Blaise Barney
 * LAST REVISED: 04/02/05
 ******************************************************************************/
#include <stdio.h>
#include <stdlib.h>

#include <mpi/mpi.h>

int main(int argc, char *argv[]) {
    int numtasks, rank, dest, source, rc, count, tag = 1;
    char inmsg, outmsg = 'x';
    MPI_Status Stat;

    MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &numtasks);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);

    if (rank == 0) {
        if (numtasks > 2)
            printf("Numtasks=%d. Only 2 needed. Ignoring extra...\n", numtasks);
        dest = 1;
        source = 1;
        rc = MPI_Send(&outmsg, 1, MPI_CHAR, dest, tag, MPI_COMM_WORLD);
        rc = MPI_Recv(&inmsg, 1, MPI_CHAR, source, tag, MPI_COMM_WORLD, &Stat);
    }

    else if (rank == 1) {
        dest = 0;
        source = 0;
        rc = MPI_Recv(&inmsg, 1, MPI_CHAR, source, tag, MPI_COMM_WORLD, &Stat);
        rc = MPI_Send(&outmsg, 1, MPI_CHAR, dest, tag, MPI_COMM_WORLD);
    }

    if (rank < 2) {
        rc = MPI_Get_count(&Stat, MPI_CHAR, &count);
        printf("Task %d: Received %d char(s) from task %d with tag %d \n", rank,
               count, Stat.MPI_SOURCE, Stat.MPI_TAG);
    }

    MPI_Finalize();
}
